Blackboard stencil



Aug. 17, 1937. w, H C RBET 2,090,186

BLACKBOARD STENCIL Filed Jan. 11, 1935 INVENTOR Maia Cor]? Patented Aug. 17, 1937 UNITED STATES PATENT OFFICE 1 Claim.

The present invention relates to stencils particularly used in association with blackboards or the like, and to the method for using the same.

In schools and particularly during the teaching of a subject which requires a base .diagram of some form, the instructor, when demonstrating upon the blackboard is impelled to draw, according to his or her best abilities, said diagram upon which the demonstration or discussion is based. When plotting charts or graphs as applied to chemistry, logic, algebra, etc., certain forms of abscissa and ordinate lines are necessary; when discussing the physical and political attributes of a country or continent, maps in outline are necessary; and similarly, when any of the technical, mechanical, civic and economic subjects are under discussion, some cer tain base diagram is required.

In certain instances, it is the province of the student to draw the necessary base diagram before he or she can demonstrate a problem. As can readily be understood, to do this in a free hand manner, no matter how expertly, would consume a great deal of time unnecessarily.

This invention, therefore, seeks to provide means and to employ a simple method for attaining such base diagrams in a quick, expeditious manner without dependence upon the skill of the person.

Another object of the invention is to provide stencil means which is portable from one portion of a blackboard to another and which is wound on a shade roller so that when the stencil is drawn down over the blackboard area, by merely tapping the surface of the stencil with a blackboard eraser, there is reproduced in chalk upon the blackboard. the diagram which is on the stencil, the shade roller affording means to remove the stencil from in front of the reproduction.

These and other objects of the invention and the means for their attainment will become more apparent from the following detailed specification, based on the accompanying drawing in which preferred forms of the invention are illustrated, and in which:

Fig. l is a front view of a portion of a blackboard showing a stencil applied thereto and also indicating the reproduction therefrom.

Fig. 2 is an enlarged vertical sectional view showing the manner of use.

Fig. 3 is a front view of a modified form of the invention.

Referring to the drawing in greater detail, the blackboard is shown at 5 with its usual form of top rail 6 and bottom rail 1. This bottom rail, as is usual is formed as a trough in which may be supported pieces of chalk and one or more erasers 8.

The stencil 9, is preferably of a flexible, durable material such as fabrics employed in window shades or may be made of rubber or oilcloth, and is provided at its bottom end with stiffening means Hi. In the manner of a window shade, the stencil is adapted to be rolled around a roller H supported in the frame or bracket l2. This bracket, in a suitable manner, may be hung as at l3 to the top rail 6 or at any other suitable place so when the bottom of the stencil is pulled it will overlie the face of the blackboard as shown.

As herein contemplated, the stencil sheet is provided with perforations I4 which outline the diagram thereon. In the case of graph diagrams (an example being illustrated in Figure 1) the lines of the diagram are formed by a series of these perforations, the intersection between two lines being formed by a somewhat larger perforation as shown at I5.

When it is desired to reproduce the diagram on the stencil to the face of the blackboard, the stencil is pulled down as shown in the left hand portion of Figure 1 and a blackboard eraser 8, the felt erasing portion of which is impregnated with chalk powder, is tapped against the surface of the stencil as shown in Figure 2 so the chalk powder will pass through the perforations and adhere to the blackboard. The result of such action is shown at I6 and is now suitable for use for the purpose intended.

If more than one diagram is wanted, it is only necessary to move the frame l2 from place to place, as desired, and in this manner, while one diagram is being worked on, others may be reproduced elsewhere on the blackboard.

In the form of the invention shown in Figure 3, the stencil 9 is shown as provided with a frame ll which may be rested upon the rail I and then used as above described.

As can be seen from the foregoing, a simple device for the purpose is provided and that the method employed is similarly simple. It should be borne in mind, however that changes may well be made without departing from the true spirit and scope of the invention as set forth in the following claim.

Having thus described my invention, what I claim as new and. desire to secure by Letters Patent, is:

As a new article of manufacture, a stencil comprising a flexible sheet having perforations outlining a foundation diagram adapted for use adjacent the face of a blackboard, a stiffening member for the free end of the sheet, a spring roller upon which the sheet may be wound, and a bracket to support said roller for rotation.

WILLIAM H. CORBETT. 

